如何从活动访问服务的变量

Question

我知道，为了从活动访问服务的方法，我们应该绑定服务。

但是，如果我们只想获得服务中变量的值，我们可以像这样访问它而不绑定吗？

int myActivityVar = myService.myServiceVar;

它有效，但我不确定它是否有任何内存泄漏或任何其他问题。

Answer 1

解决方案

• Activity将向Service发送BroadcastReceiver以请求获取数据。

• Service将注册BroadcastReceiver，当接收到来自Activity的广播消息时，它将准备结果数据并使用ResultReceiver将其发送回Activity。

实施

MyService.java

public class MyService extends Service {
public static final String ACTION_GET_DATA = "ACTION_GET_DATA";
public static final String EXTRA_RECEIVER = "EXTRA_RECEIVER";
public static final String EXTRA_DATA = "EXTRA_DATA";
public static final int RESULT_OK = 1;
public static final int RESULT_FAILED = 0;
// The data of the Service that the Activity want to access.
private int myServiceVar = 100;
private final BroadcastReceiver onGetDataReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// Send result data to the activity
ResultReceiver receiver = intent.getParcelableExtra(EXTRA_RECEIVER);
Bundle resultData = new Bundle();
resultData.putInt(EXTRA_DATA, myServiceVar);
receiver.send(RESULT_OK, resultData);
}
};
@Override
public void onCreate() {
super.onCreate();
registerReceiver(onGetDataReceiver, new IntentFilter(ACTION_GET_DATA));
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// TODO: Your code logic goes here.
return Service.START_STICKY;
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
}

MainActivity.java

private void getDataFromService() {
Handler mainHandler = new Handler(Looper.getMainLooper());
ResultReceiver receiver = new ResultReceiver(mainHandler) {
@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
if (resultCode == MyService.RESULT_OK) {
int data = resultData.getInt(MyService.EXTRA_DATA);
Log.i(TAG, "Received data = " + data);
}
}
};
Intent intent = new Intent(MyService.ACTION_GET_DATA);
intent.putExtra(MyService.EXTRA_RECEIVER, receiver);
sendBroadcast(intent);
}